/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.test.web.servlet.result;

import org.hamcrest.Matcher;
import org.springframework.test.web.servlet.ResultMatcher;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.springframework.test.util.AssertionErrors.assertEquals;
import static org.springframework.test.util.AssertionErrors.assertTrue;

/**
 * Factory for "output" flash attribute assertions.
 *
 * <p>An instance of this class is typically accessed via
 * {@link MockMvcResultMatchers#flash}.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
public class FlashAttributeResultMatchers {

    /**
     * Protected constructor.
     * Use {@link MockMvcResultMatchers#flash()}.
     */
    protected FlashAttributeResultMatchers() {
    }


    /**
     * Assert a flash attribute's value with the given Hamcrest {@link Matcher}.
     */
    @SuppressWarnings("unchecked")
    public <T> ResultMatcher attribute(final String name, final Matcher<T> matcher) {
        return result -> assertThat("Flash attribute '" + name + "'", (T) result.getFlashMap().get(name), matcher);
    }

    /**
     * Assert a flash attribute's value.
     */
    public <T> ResultMatcher attribute(final String name, final Object value) {
        return result -> assertEquals("Flash attribute '" + name + "'", value, result.getFlashMap().get(name));
    }

    /**
     * Assert the existence of the given flash attributes.
     */
    public <T> ResultMatcher attributeExists(final String... names) {
        return result -> {
            for (String name : names) {
                assertTrue("Flash attribute '" + name + "' does not exist", result.getFlashMap().get(name) != null);
            }
        };
    }

    /**
     * Assert the number of flash attributes.
     */
    public <T> ResultMatcher attributeCount(final int count) {
        return result -> assertEquals("FlashMap size must be " + count, count, result.getFlashMap().size());
    }

}
